RDMA/siw: Remove kmap()

kmap() is being deprecated and will break uses of device dax after PKS
protection is introduced.[1]

These uses of kmap() in the SIW driver are thread local.  Therefore
kmap_local_page() is sufficient to use and will work with pgmap protected
pages when those are implemnted.

There is one more use of kmap() in this driver which is split into its own
patch because kmap_local_page() has strict ordering rules and the use of
the kmap_mask over multiple segments must be handled carefully.
Therefore, that conversion is handled in a stand alone patch.

Use kmap_local_page() instead of kmap() in the 'easy' cases.

[1] https://lore.kernel.org/lkml/20201009195033.3208459-59-ira.weiny@intel.com/

Link: https://lore.kernel.org/r/20210622061422.2633501-4-ira.weiny@intel.com


Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>